Sponson filler material? - 97 GSX

[Ankeneyou]

I'm restoring a 97 GSX and took the sponsons off to paint them black. I know the GSX sponsons are notorious for breaking and people want 40-50 a piece for used ones.

They seem pretty fragile once off the ski, so before painting them I was thinking about filling them with Bondo glass or something else to give them a little more strength.

Any ideas on the best material which won't absorb water? I'm not too worried about adding a few pounds to the ski by filling them.

 

[racerxxx]

Clear silicone caulk. Fill, scrape with a straight edge. Let cure, install. Caulk is available at your local home improvement store.

 

[mikidymac]

Racer, wouldn't silicone flex too much to prevent the sponsons from breaking? I would think you would want something more rigid.

 

[1of500]

2 part epoxy as long as it's compatible with the plastic

 

[racerxxx]

Racer, wouldn't silicone flex too much to prevent the sponsons from breaking? I would think you would want something more rigid.

No, it's very dense when cured. I honestly think it's water that's forced in the pockets and it has no where to go but the weakest point of exit. Fill that pocket and the water can't enter. Just about every gsx suffers from this, no way everyone hits something on the underside of the sponsons.

 

[Ankeneyou]

Thanks for the ideas fellas. I thought of silicone but also questioned if it would really add any more structural integrity. I thought maybe it would just help hold the pieces of the sponsons together after it cracked, lol.

Ok also thought of 5200 quick dry, but I also don't want to spend $60 in materials.

I may just end up doing the silicone or if I can find some cheap epoxy online.

 

[racerxxx]

It's gonna add MORE than what's there now, am I right? LOL

 

[gsus67]

You can always try the expanding foam from Home Depot or Lowe’s. Just spray it, let it expand then just trim it flush.

 

[1of500]

You can always try the expanding foam from Home Depot or Lowe’s. Just spray it, let it expand then just trim it flush.

That will hold water

 

[WhiskeyD]

2 part epoxy as long as it's compatible with the plastic

Thats what I was thinking as well

 

[Ankeneyou]

Ok, so I poured some water in the sponsons earlier and determined I need about 8.5 oz of material as filler per sponson.

I found 16oz epoxy on Amazon for $19, which I'll mix with some saw dust to give some strength and make up for the missing ounce I need to fill.

Thanks again for all the replies I'll let you know how it works out.

 

[Kwik_uk]

Use chopped strand glass instead of sawdust. Stronger and doesn’t absorb water. I bought a huge bag of it for £3-4 years ago, and still have loads left. You can use it for all sorts.

Talc is also a cheap common filler.

 

[Ankeneyou]

Well I got my Amazon epoxy for $8.28 so will be trying this out tonight and let you know how it goes.

They had a marine version of this same epoxy for a few bucks more but it looks like the only difference is it the marine can cure underwater.

 

[Matt Braley]

Looking forward to the results. $9 is not bad for 32oz of anything and that stuff has a good name.

 

[Ankeneyou]

I got one side done last night before heading out for dinner. This stuff definitely is a "paste" as it says as both parts come out very thick and it takes some effort to mix.

I thinned it a bit and started dropping into the sponson with a plastic spoon. I definitely should have thinned it more as it wasn't the easiest to make sure it got in all the voids.

After curing overnight it's already mostly hard but I will go over this on again with another thinned coat to make up for some air bubbles that came up. It definitely feels like a solid part now, and hopefully won't break once on the ski.

I'll do some testing on how much I can thin out the epoxy this weekend and ensure it still cures before attempting the 2nd one. I'll definitely be ordering more of this stuff to have around for the price and how well it works. This stuff would have made it much easier to glue my fuel pump mount to the side of my spx hull and would't run before curing.

 

[Ankeneyou]

I also ended up getting a new in box set of beach house sponsons off fleabay for both the XPL and GSX this last week, but I'll be leaving these stock "filled" sponsons on for now.

 

[Matt Braley]

Yeah you just sniped me on those GSX sponsons

 

[Ankeneyou]

Yeah you just sniped me on those GSX sponsons

Haha, sorry Matt. He posted both last week for 150 buy it now, 99 starring bid. I grabbed the xpls and figured the gsx might sell for the 99 regular price so I just put in a bid instead of buy it now. Ended up paying 2.50 more than if I had just done buy it now.

Heck a super clean set for the gsx sold for like 70 in December that I missed.

 

[DerekI]

Had a broken stock sponsons and boutique the worx sponsons what a difference in just the ride alone let alone cutting corners. And solid material and adjustable. Up to you but worth the $ if you change out yourself

 

[Ankeneyou]

Yeah that's why I bought the beach house to try later on. I've got them on other skis, but this GSX will be a ski left at the dock at a lake house for people to ride. Since it will largely be a loaner ski, I don't want it taking tight turns and tossing people off who aren't expecting it to grab on the water, lol.

 

[dgoodwin10]

Great idea. I have a 97 GSX with both sponsons still in tact- I need to do this before I crack one.

Granted, it needs to actually run first...

 

[Minnetonka4me]

The left one is the one we always get calls in. My theory is people mount everything from the left from horse days... So when it's sitting on shore people sit on them from the left, tip it that way and then they catch on a rock or something. I'd think epoxy would be best, I'd prob do it in 3 steps vs filling on first try.

 

[Ankeneyou]

Well I finished the 2nd sponson over the weekend. I thinned the epoxy paste with laquer thinner to a syrup consistency. Next I spooned it into the 2nd sponson and topped off the first one as well.

I was a little worried at first as it was still liquid after 24 hours so I wasn't sure it would set up. 48 hours later it's almost completely set up, but I'll let it sit for a week before mounting it back on the ski.

These things almost feel like weapons now they are so solid! I think they will hold up really well. Total cost was $17 since I lost so much epoxy the first round experimenting that I had to buy a 2nd one. I'd definitely recommend two just to be safe and I'm sure I can find more uses for the leftovers.

 

[Matt Braley]

Great thread Ank